code: def create_feature_names(sfa_words):
      """Create feature names."""
      feature_names = set()
      for t_words in sfa_words:
          for t_word in t_words:
              feature_names.add(t_word)
      return feature_names
  
file_path: sktime/sktime/transformations/panel/dictionary_based/_sfa_fast_numba.py
imports: import math
  from warnings import simplefilter
  import numpy
  from sktime.utils.numba.njit import njit
  from sktime.utils.validation._dependencies import _check_soft_dependencies
label_desc: Use image node_id 8 for calling a global function with example usage: create_feature_names(sfa_words) and returns: feature_names